Method and apparatus for coating interior surfaces of medical devices

ABSTRACT

A coating can be applied to an endolumenal wall of a medical device by positioning an optical fiber within the lumen, providing a photo-activated chemical to contact the endolumenal wall, supplying the optical fiber with radiation capable of activating the chemical within the lumen, and withdrawing the optical fiber from the lumen at a controlled rate while the radiation is being emitted from the optical fiber to activate the chemical in close proximity to the endolumenal wall.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending application Ser. No.11/159,707 filed Jun. 23, 2005, which in turn is related to and claimsall benefits of U.S. Provisional Applications Ser. No. 60/582,694 filedJun. 24, 2004.

1. TECHNICAL FIELD

The present invention relates to medical devices, particularly surgicalinstruments and prostheses, having elongated and generally opaque wallstructures surrounding an elongated lumen such as catheters,introducers, needles, stent frames and stent grafts. The inventionparticularly relates to methods and apparatus for applying selectedcoatings to endolumenal surfaces of such devices.

2. GENERAL BACKGROUND

Catheters, introducers, and other similar medical devices havingelongated lumens are used to deliver diagnostic and therapeutic agentsand appliances to remote locations through the vascular systems withinthe body of a patient. Needles, stent frames, stent grafts and othersimilar medical devices have elongated, although, generally,proportionally somewhat shorter lumens that are used to provide apathway for vital fluids to and through the tissue and vascular systemsof the patent. Further, when expanded radially, stent frames have a moreor less porous structure rather than the substantially continuous wallcharacter of the other medical devices considered herein.

Considerable attention has been given to controlling the physicalinteraction between such devices and the various structures and fluidsthrough which the devices are moved by manipulating the surfacechemistry of various portions of the devices. For example, U.S. Pat. No.6,706,025 to Engelson, et al., discloses coating various longitudinalsegments of the exterior surface of a catheter with lubricioushydrophilic polymers selected to provide various frictionalcharacteristics to the different longitudinal segments. The selectedpolymeric coatings are applied by spraying a solution or suspension ofthe polymers or of oligomers of the monomers onto the catheter, or bydipping the catheter into the solution or suspension after sealing theopen ends of the catheter. The coating is allowed to dry. During orafter drying, the coating can be irradiated with ultra-violet light orionizing radiation to promote polymerization and cross-linking of thecoating to the exterior surface of the catheter. The coating procedurecan optionally be repeated so that one or more additional coatings areapplied in a similar manner. No means are disclosed to specificallyapply any coating liquids to the endolumenal wall of the catheter. Nomeans are disclosed to provide irradiation to encourage thepolymerization of any coating fluids that might accidentally flow intothe lumen of the catheter. As a result, the interior surface chemistryof the catheter is essentially totally unaffected by the procedures andchemical agents disclosed in Engelson.

Other processes for coating stent frames are known from includingbrushing, wiping, pad printing, ink-jet printing, electrostatic liquidspraying, and electrostatic powder coating. The desirability of coatingstent frames with a polymer dissolved in a solvent optionally containinga therapeutic substance such as actinomycin D, paclitaxel, docetaxel, orrapamycin is known. Known polymers that can be used to coat stents withsuch substances include, for example, a number of polymethacrylates,polycaprolactone, and polysilanes. The therapeutic substances can alsobe anti-neoplastic agents, anti-proliferative agents, anti-inflammatoryagents, growth control factors, antibiotics, antioxidants, andcombinations thereof.

However, there remains a need for methods and apparatus to apply adesired surface chemistry to the endolumenal walls of catheters,introducers, needles, stent frames, stent grafts, and other similarlystructured medical devices, to achieve the recognized benefits of suchmodifications in surface chemistry. There is a particular need to coatthe endolumenal walls or surfaces of stent frames and stent grafts withsubstances that will effectively inhibit targeted adverse physiologicalreactions, such as restenosis, caused by uncoated surfaces of medicaldevices inserted or implanted in a patient's body.

BRIEF SUMMARY

Apparatus for applying a coating to an endolumenal wall of a medicaldevice includes an optical fiber dimensioned to fit within the lumen ofthe medical device. The optical fiber must be capable of carryingradiation having a suitable wavelength to interact with a chemical agentof the coating material to be applied to the endolumenal wall. Theoptical fiber must have a first end that is able to be coupled to asource of such radiation. The source of radiation can include intensitycontrols to govern the amount of radiation to be delivered to theoptical fiber first end.

The optical fiber desirably has a second end with a structure conduciveto illuminate the endolumenal wall adjacent to the second end of theoptical fiber. The optical fiber second end can take the form of adivergent lens that causes radiation passing through the second end tobe spread onto that portion of the endolumenal surface that is beyondthe optical fiber second end. The optical fiber second end can also takethe form of an inwardly protruding conical reflective surface thatcauses radiation to be reflected outward through the side wall of theoptical fiber.

A coating material supply provides at least a monomolecular film of thecoating material immediately adjacent to the optical fiber second end.The coating material supply can take the form of a reservoir of thecoating material of a size suitable to permit the medical device to beat least partially immersed in the coating material. The coatingmaterial supply can also take the form of a pump coupled to a reservoirof the coating material and to the medical device in such a manner as topermit a flow of the coating material to be supplied to and/or throughthe lumen of the device. The coating material supply can also take theform of a source of the coating material to a capillary space betweenthe optical outer surface and the endolumenal wall, the capillary forcebeing relied upon to distribute the coating material to a positionadjacent to the optical fiber second end. A flow of gas can be used toinhibit excessive coating.

The second end of the optical fiber desirably travels at least oncethrough at least the length of any portion of the lumen to which thecoating material is to be applied. The second end of the optical fibercan travel through the entire length of the lumen at a controlled rateof speed, which can vary from segment to segment of the lumen. The rateof speed can be related to the amount of optical energy needed to causea desired reaction of the photo-active component of the coatingmaterial. Suitable position and drag sensors can be included to aid inthe control of the traveling characteristics of the optical fiber withrespect to the lumen.

A coating can be applied to an endolumenal wall of a medical device bypositioning an optical fiber within the lumen, providing aphoto-activated chemical to contact the endolumenal wall, supplying theoptical fiber with radiation capable of activating the chemical withinthe lumen, and withdrawing the optical fiber from the lumen at acontrolled rate while the radiation is being emitted from the opticalfiber to activate the chemical in close proximity to the endolumenalwall. This method can be modified or repeated as desired to achieve acoating of desired character and thickness. The exact chemical make-upand characteristics of the coating material is not central to thepresent case, which is directed to apparatus and methods for applyingcoatings of various character to the endolumenal wall of a medicaldevice, except that the coating material must have a component thatreacts to the radiation carried by the optical fiber.

The previously described method and apparatus, and the attributes andcharacteristics of same, will be better understood from the followingdetailed description, when read in conjunction with the accompanyingdrawings, wherein like reference characters refer to like partsthroughout the several views and different embodiments of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a first embodiment of a distal endof an apparatus of the present invention.

FIG. 2 is a cross-sectional view of a second embodiment of a distal endof an apparatus of the present invention.

FIG. 3 is a cross-sectional view of a proximal end of an apparatus ofthe present invention.

FIG. 4 is a block diagram of an apparatus of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Apparatus 10 for applying a coating to an endolumenal wall 12 of amedical device 14 is shown in FIG. 1. The medical device 14 can be, forexample, a catheter, introducer, needle, stent frame or stent graft. Theapparatus 10 includes an optical fiber 16 having a distal end 18. Theoptical fiber 16 is surrounded by an opaque wall 20. The opaque wall 20can be further surrounded by a fluid-carrying channel 22 having a distalend 24. An outer wall 26 can surround the fluid-carrying channel 22. Aplurality of openings 28 can be provided in the outer wall 26 adjacentto the distal end 24 of the fluid-carrying channel 22. The outer wall 26can also be opaque to radiation having a suitable wavelength to interactwith a chemical agent of the coating material to be applied to theendolumenal wall. The distal end 18 of the optical fiber 16 isconfigured to disperse any radiation traveling down the optical fiber 16onto the endolumenal wall 12 of the medical device 14. The optical fiber16 must be capable of carrying radiation having a suitable wavelength tointeract with a chemical agent of the coating material to be applied tothe endolumenal wall 12. The configuration of the distal end 18 can be asimple divergent lens shape 30 that will disperse the light in a wellknown manner to interact with any fluid 32 that may be dispensed ontothe endolumenal wall 12 through the openings 28.

The fluid 32 can include lubricious hydrophilic polymers, such as, forexample, a polysiliane or a polyfluoroethylene selected to providevarious frictional characteristics. The fluid 32 can also include, forexample, a therapeutic substance such as actinomycin D, paclitaxel,docetaxel, or rapamycin. The fluid 32 can also include, for example asolvent such as, for example, water, alcohol or ether. The fluid 32 canalso include, for example, therapeutic substances can also beantineoplastic agents, antoproliferative agents, anti-inflammatoryagents, growth control factors, antibiotics, antioxidants, andcombinations thereof. The fluid 32 must have a component that reacts tothe radiation from the distal end 18 of the optical fiber 16. Suitableradiation reactive components include, for example, anthraquinone,benzophenone, thioxanthone, and acetophenone.

An alternative structure for the apparatus 10 is shown in FIG. 2 whereinthe distal end 18 of the optical fiber 16 can include an inwardlyprotruding conical surface 34. The conical surface 34 can be formed toreflect any radiation traveling down the optical fiber so that theradiation is directed radially outward through side wall 36 to interactwith any fluid 32 that may be dispensed onto the endolumenal wall 12through the openings 28. The openings 28 can be spaced around the outerwall 26 in any pattern that will permit at least a monomolecular film ofthe fluid 32 to be dispensed onto the endolumenal wall 12. When the wall12 of the medical device 14 is continuous, the thickness of the film offluid 32 can be controlled by providing a flow a gas between the outerwall 26 and the endolumenal wall 12. The flow of gas between the outerwall 26 and the endolumenal wall 12 can also act as a centeringmechanism for the apparatus 10 within the medical device 14, which maycontribute to a more uniform distribution of the fluid 32. The outerwall 26 of the apparatus 10 can be dimensioned to fit within, but bemovable with respect to, the endolumenal wall 12 of the medical device14. The outer wall 26 can be dimensioned to define a capillary spacebetween the outer wall 26 and the endolumenal wall 12 to aid in thetransport of the fluid 32 out of the channel 22 and onto the endolumenalwall 12.

The apparatus 10, of either FIG. 1 or FIG. 2, can also include aproximal end 38 as shown in FIG. 3. The proximal end 38 can include aliquid inlet bushing 40 that surrounds the optical fiber 16. A moldedfitting 42 can couple the bushing 40 to the outer wall 26. The inletbushing includes an opening 41 for receiving the fluid 32 from a sourcedescribed below. The optical fiber 16 can pass through an end wall 44 ofthe bushing 40 toward a suitable source of radiation having a suitablewavelength to interact with a chemical agent of the coating material tobe applied to the endolumenal wall. The bushing 40, including the endwall 44, can also be opaque to radiation having a suitable wavelength tointeract with the reactive chemical agent of the coating material. Theend wall 44 can be coupled to the opaque wall 20 with an O-ring or otherseal 45 to prevent the fluid 32 from leaking from the bushing 40 aroundthe opaque wall 20.

The apparatus 10 can include a plenum 43 that can be coupled to an end13 of the medical device 14. The plenum 43 can include an inlet 39coupled to a source of gas, which can be air or another gas such as, forexample, nitrogen, that is pressurized sufficiently to cause alongitudinal flow of gas between the outer wall 26 and the endolumenalwall 12 of the medical device 14. The gas can be selected to have avapor component that will contribute to the development of a uniformthickness of the film of fluid 32. The plenum 43 can include an end wall37 having an opening 35 for receiving the optical fiber 16, opaque wall20 and outer wall 26. A seal 33 can be provided between the opening 35and outer wall 26 to prevent escape of the gas through the opening 35.

The apparatus 10 is schematically shown in FIG. 4 to include an opticalfiber 16 coupled to a source 46 of radiation of a suitable wavelength tointeract with the chemical agent of the coating material. The radiationsource 46 can include an intensity control 48 to govern the amount ofradiation to be delivered to the optical fiber. The radiation source 46can also include a wavelength tuning or selection control 50 forselecting radiation of a suitable wavelength for interaction with thechemical agent of the coating material. The apparatus 10 can include asupply 52 of liquid containing a coating material to be applied to theendolumenal wall 12. The liquid supply 52 can include a reservoir 54 anda pump 56. The liquid supply 52 can be connected to the bushing 40 shownin FIG. 3. A gas supply 68 can supply a flow of a gas to the plenum 43in sufficient quantity to cause a flow of gas longitudinally between theendolumenal wall 12 and the optical fiber 16. The apparatus 10 can alsoinclude a traction device 58 for causing longitudinal movement betweenthe optical fiber 16 and the endolumenal wall 12 of the medical device14. The traction device 58 can be coupled to or include a motor 60 witha speed control 62 for regulating the rate of relative movement betweenthe optical fiber 16 and the medical device 14. The traction device 58can also be coupled to a position sensor 64, a drag sensor 66, and othercontrols for sensing and governing the rate of movement, application ofthe liquid, and application of radiation.

Using an apparatus like those disclosed in the preceding figures, acoating can be applied to an endolumenal wall of a medical device in avariety of related processes that can include the steps of positioningan optical fiber with a distal end within the lumen, providing aphoto-activated chemical in contact with the endolumenal wall adjacentto the optical fiber distal end, supplying the optical fiber withradiant energy of a wavelength selected to interact with thephoto-activated chemical, and moving the optical fiber with respect tothe lumen at a controlled rate during the photo activation. The processsteps can be repeated as often as necessary to deposit the desiredamount of photo-activated chemicals on the endolumenal wall. The processsteps can be practiced over the entire length of a selected device orlimited to only selected regions within the lumen.

The foregoing detailed description should be regarded as illustrativerather than limiting, and the following claims, including allequivalents, are intended to define the spirit and scope of thisinvention.

1-9. (canceled)
 10. Apparatus for applying a coating to an endolumenalwall of a medical device, the apparatus comprising: an optical fiberdimensioned to be received within a lumen of a medical device, theoptical fiber having a first end and a second end, the second end beingadapted to disperse radiation traveling through the optical fiber; afluid-carrying channel surrounding the optical fiber and having an outerwall with a distal opening adjacent the optical fiber second end; asupply of a fluid disposed within the fluid-carrying channel to bedispensed onto said endoluminal wall of the medical device adjacent tothe optical fiber second end, the fluid having a photo-activatedcomponent; a source of radiation coupled to the optical fiber first end,the radiation being transmittable by the optical fiber and interactivewith the photo-activated component of the fluid; and a transit controlconfigured to move at least one of the second end of the optical fiberand the fluid-carrying channel through a selected portion of the medicaldevice lumen at a controlled rate.
 11. The apparatus of claim 10,further comprising a reservoir coupled to the fluid-carrying channel,the reservoir containing the fluid supply and including a pump coupledto and configured to move the fluid from the reservoir, through thefluid-carrying channel, and to the distal opening.
 12. The apparatus ofclaim 10, wherein the outer wall of the fluid-carrying channel ispositioned from the endoluminal wall of the medical device by acapillary space to aid in the dispensing of the fluid onto saidendoluminal wall.
 13. The apparatus of claim 10, wherein the fluidsupply comprises a dispenser situated adjacent to the optical fibersecond end, and a tubular member coupled between a reservoir of thefluid and the dispenser, the tubular member having a length sufficientto locate the fluid dispenser at any desired position within the lumenof the medical device.
 14. The apparatus of claim 10 further comprisinga plenum surrounding the optical fiber and coupled to a supply of gas tocreate a flow of gas within the lumen of the medical device.
 15. Theapparatus of claim 14 further comprising a gas flow sensor configured tosense the amount of gas flow entering into the lumen of the medicaldevice.
 16. The apparatus of claim 10, wherein the outer wall of thefluid-carrying channel includes a surface facing the endolumenal wall,at least a portion of the surface being opaque.
 17. The apparatus ofclaim 10, wherein the second end of the optical fiber is configured tolimit emission of radiation therefrom to only selected portions of saidendolumenal wall.
 18. The apparatus of claim 10, wherein thefluid-carrying channel further comprises at least one opening formedthrough the outer wall.
 19. The apparatus of claim 18, wherein the atleast one opening comprises a plurality of openings spaced around theouter wall, wherein the spacing between the openings is configured topermit the formation of a monomolecular film of the fluid along saidendolumenal wall.
 20. The apparatus of claim 10, further comprising anopaque wall surrounding the optical fiber and disposed radially inwardfrom the outer wall of the fluid-carrying channel.
 21. The apparatus ofclaim 10, wherein the transit control is further configured to move thesecond end of the optical fiber and the fluid-carrying channelsimultaneously through the selected portion of the medical device lumenat the controlled rate.
 22. The apparatus of claim 10, wherein thetransit control further comprises a traction device adapted to permitrelative movement between the at least one of the second end of theoptical fiber and the fluid-carrying channel and the selected portion ofthe medical device lumen.
 23. The apparatus of claim 22, wherein thetransit control further comprises a position sensor coupled to thetraction device and configured to sense the relative position betweenthe at least one of the second end of the optical fiber and thefluid-carrying channel and the selected portion of the medical devicelumen.
 24. The apparatus of claim 22, wherein the transit controlfurther comprises a drag sensor coupled to the traction device andconfigured to sense the relative tension between the at least one of thesecond end of the optical fiber and the fluid-carrying channel and theselected portion of the medical device lumen.
 25. The apparatus of claim10, wherein the traction device further comprises a motor with a speedcontroller configured to regulate the rate of relative movement betweenthe at least one of the second end of the optical fiber and thefluid-carrying channel and the selected portion of the medical devicelumen.
 26. The apparatus of claim 10, wherein the transit controlfurther comprises a fluid flow sensor configured to sense the amount offluid flow disposed within the fluid-carrying channel.
 27. The apparatusof claim 10, wherein the radiation source further comprises an intensitycontroller configured to govern the amount of radiation to be deliveredto the optical fiber.
 28. The apparatus of claim 10, wherein theradiation source further comprises a wavelength tuner configured topermit selection of the wavelength of radiation suitable for interactionwith the photo-activated component of the fluid.
 29. The apparatus ofclaim 10, wherein the second end of the optical fiber extends beyond thedistal opening of the fluid-carrying channel.